This application claims the benefit of Korean Application No. 2002-72343, filed Nov. 20, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates, in general, to push buttons and, more particular, to a push button which is designed such that it is not broken or damaged even when an excessive external force is applied to the push button.
2. Description of the Related Art
As is well known to those skilled in the art, a push button is a device which is provided on a control panel of various kinds of electrical devices to operate a switch installed inside the control panel so that the switch is turned on or off.
FIG. 1 illustrates a conventional push button.
The conventional push button 2 is installed in a seat depression 1a which is provided on a control panel 1. The push button 2 includes a cylindrical button unit 3 which is opened at its lower portion. A rod-shaped push unit 4 extends from the button unit 3, and passes through the seat depression 1a to push a switch 6 which is provided at a predetermined position inside the control panel 1. A spring 5 elastically biases the button unit 3 in a direction away from a bottom of the seat depression 1a. 
Thus, when an external force is applied to the button unit 3, the spring 5 is compressed by the external force, so the button unit 3 and the push unit 4 are moved toward the switch 6. Due to the movement of the button unit 3 and the push unit 4, an end of the push unit 4 pushes the switch 6 so that the switch 6 is turned on or off. Meanwhile, when the external force is released from the button unit 3, the spring 5 is returned to its original position, thus returning the button unit 3 and the push unit 4 to their original positions.
However, the conventional push button 2 has a problem that, when an excessive external force is applied to the button unit 3, the external force is transmitted through the push unit 4 to the switch 6 and a circuit board 7 to which the switch 6 is mounted, so the switch 6 and the circuit board 7 may be damaged or broken.
Further, the conventional push button 2 has another problem that, when a user pushes the button unit 3 to press the switch 6 by the push unit 4, a reaction force opposite to the user""s force is transmitted through the push unit 4 and the button unit 3 to the user, so a manipulation feeling is poor.
Accordingly, it is an aspect of the present invention to provide a push button, which is designed such that a switch or a circuit board is not damaged or broken even when an excessive external force is applied to the push button.
Another aspect of the present invention is to provide a push button having an excellent manipulation feeling.
A further aspect of the present invention is to provide an electrical device having the push button, which is designed such that a switch or a circuit board of the electrical device is not damaged or broken even when an excessive external force is applied to the push button.
Additional aspects and advantages of the invention will be set forth in part in the descripton which follows and, in part, will be obvious from the description, or may be leamed by practice of the invention.
The foregoing and/or other aspects of the present invention are achieved by providing a push button, including a control panel having a switch controlling a function, a seat depression provided on the control panel, a button unit seated in the seat depression in such a way as to be movable by a predetermined distance, a push unit passing through the seat depression and moving by a force transmitted from the button unit to push the switch, and first and second springs having different spring constants, respectively responding to the force transmitted from the button unit.
Further, the push unit includes a support part arranged between the button unit and the seat depression, and a push part extending from the support part and passing through the seat depression to push the switch. The first spring is provided between the button unit and the support part, and the second spring is provided between the support part and the seat depression, the first spring having a larger spring constant than the second spring.
In addition, the push unit integrally extends from the button unit, and the first and second springs are integrated into a single structure and provided between the button unit and the seat depression.
Further, the seat depression is provided with a locking hole to lock the button unit to the seat depression, with a through hole being provided on the seat depression to allow the push part to pass through the seat depression. The button unit is provided with a locking hook, the locking hook being locked to the locking hole of the seat depression so that the button unit is seated in the seat depression in such a way as to be movable by the predetermined distance.